System and method for providing an integrated reactor

ABSTRACT

A system and method for providing an integrated indirectly fired reactor and steam generator are disclosed. According to one embodiment, the reactor comprises an indirect heating zone heating water and generating steam, a mixing zone mixing feedstock and the steam and providing a mixture of the feedstock and the steam, and a reaction zone comprising a first reactor and a second reactor. The first reactor converts the mixture to a first syngas at a first temperature. The second reactor converts the first syngas to a second syngas at a second temperature, the second temperature being higher than the first temperature.

The present application is a continuation of U.S. patent applicationSer. No. 13/437,761 titled “SYSTEM AND METHOD FOR PROVIDING ANINTEGRATED REACTOR,” filed on Apr. 2, 2012 that issued on Mar. 25, 2014as U.S. Pat. No. 8,680,163 B2, which is a continuation of U.S. patentapplication Ser. No. 12/688,667 titled “SYSTEM AND METHOD FOR PROVIDINGAN INTEGRATED REACTOR,” filed on Jan. 15, 2010 that issued on May 1,2012 as U.S. Pat. No. 8,168,144, which claims the benefit of andpriority to U.S. Provisional Patent Application Ser. No. 61/144,990filed on Jan. 15, 2009, each of which are hereby incorporated byreference herein in their entirety for all purposes.

FIELD

The present application relates to a system and method for generatingpower and/or producing synthetic chemicals. More particularly, thepresent invention is a system and method for providing an integratedreactor.

BACKGROUND

Global climate change and the contribution of effects by carbon dioxide(CO₂) have led to researching ways to reduce CO₂ emissions. One solutionis to capture CO₂ at its source (e.g., at a power plant) and sequestrateit before releasing to the atmosphere.

Conventional power plants use fossil fuel to generate power. Carbondioxide is an inevitable byproduct of fuel-burning process. Conventionalintegrated gasification combined cycle (IGCC) power plants utilize cleancoal power production, but their need for continuous supply of oxygenfor combusting coal makes the construction and operation of suchgasification power plant expensive limiting their scalability andreliability. In addition, as a result of partial combustion of coal withpure oxygen for heat production to drive the gasification reaction ofcoal, carbon dioxide is generated. The removal of carbon dioxide isrequired to achieve the required heating value of the produced Syngas.

The capital costs associated with oxygen production plants and gascleaning equipment are roughly 25% of the entire gasification powerplant. The production of oxygen and cleaning of combustion gases requireenergy. The more energy is produced, the more energy is spent for oxygenproduction and gas cleaning. Therefore, the operating cost for powergeneration using those conventional gasification system increases withtheir energy production capacity. This has an adverse affect on theoverall efficiency and carbon dioxide emissions. Elimination of theoxygen plant not only lowers the capital costs of a clean coal powerplant but also reduces carbon dioxide emissions.

SUMMARY

A system and method for providing an integrated indirectly fired reactorand steam generator are disclosed. According to one embodiment, thereactor comprises an indirect heating zone heating water and generatingsteam, a mixing zone mixing feedstock and the steam and providing amixture of the feedstock and the steam, and a reaction zone comprising afirst reactor and a second reactor. The first reactor converts themixture to a first syngas at a first temperature. The second reactorconverts the first syngas to a second syngas at a second temperature,the second temperature being higher than the first temperature.

The above and other preferred features, including various novel detailsof implementation and combination of elements, will now be moreparticularly described with reference to the accompanying drawings andpointed out in the claims. It will be understood that the particularmethods and apparatuses are shown by way of illustration only and not aslimitations. As will be understood by those skilled in the art, theprinciples and features explained herein may be employed in various andnumerous embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included as part of the presentspecification, illustrate the presently preferred embodiment of thepresent invention and together with the general description given aboveand the detailed description of the preferred embodiment given belowserve to explain and teach the principles of the present invention.

FIG. 1 illustrates a simplified process of oxygen-free gasification,according to one embodiment;

FIG. 2 illustrates a plot of exemplary syngas composition across atemperature range, according to one embodiment;

FIG. 3 illustrates a plot of exemplary syngas composition over apressure range, according to one embodiment;

FIG. 4 illustrates an exemplary oxygen-free gasification reactor,according to one embodiment;

FIG. 5A is a top view of a cylindrical type reactor, according to oneembodiment;

FIG. 5B is a top view of a box-type reactor, according to oneembodiment;

FIG. 6 illustrates a block diagram for an exemplary integratedgasification combined cycle, according to one embodiment; and

FIG. 7 illustrates a block diagram for an exemplary biomass to ethanolconversion, according to one embodiment.

It should be noted that the figures are not necessarily drawn to scaleand that elements of structures or functions are generally representedby reference numerals for illustrative purposes throughout the figures.It also should be noted that the figures are only intended to facilitatethe description of the various embodiments described herein. The figuresdo not describe every aspect of the teachings described herein and donot limit the scope of the claims.

DETAILED DESCRIPTION

A system and method for providing an integrated indirectly fired reactorand steam generator are disclosed. According to one embodiment, thereactor comprises an indirect heating zone heating water and generatingsteam, a mixing zone mixing feedstock and the steam and providing amixture of the feedstock and the steam, and a reaction zone comprising afirst reactor and a second reactor. The first reactor converts themixture to a first syngas at a first temperature. The second reactorconverts the first syngas to a second syngas at a second temperature,the second temperature being higher than the first temperature.

In the following description, for purposes of clarity and conciseness ofthe description, not all of the numerous components shown in theschematic are described. The numerous components are shown in thedrawings to provide a person of ordinary skill in the art a thoroughenabling disclosure of the present invention. The operation of many ofthe components would be understood to one skilled in the art.

Each of the additional features and teachings disclosed herein can beutilized separately or in conjunction with other features and teachingsto provide the present reactor. Representative examples utilizing manyof these additional features and teachings, both separately and incombination, are described in further detail with reference to theattached drawings. This detailed description is merely intended to teacha person of skill in the art further details for practicing preferredaspects of the present teachings and is not intended to limit the scopeof the claims. Therefore, combinations of features disclosed in thefollowing detailed description may not be necessary to practice theteachings in the broadest sense and are instead taught merely todescribe particularly representative examples of the present teachings.

Moreover, the various features of the representative examples and thedependent claims may be combined in ways that are not specifically andexplicitly enumerated in order to provide additional useful embodimentsof the present teachings. In addition, All features disclosed in thedescription and/or the claims are intended to be disclosed separatelyand independently from each other for the purpose of originaldisclosure, as well as for the purpose of restricting the claimedsubject matter independent of the compositions of the features in theembodiments and/or the claims. All value ranges or indications of groupsof entities disclose every possible intermediate value or intermediateentity for the purpose of original disclosure, as well as for thepurpose of restricting the claimed subject matter. The dimensions andthe shapes of the components shown in the figures are designed to helpunderstand how the present teachings are practiced but are not intendedto limit the dimensions and the shapes shown in the examples.

According to one embodiment, an integrated and indirectly firedoxygen-free gasification reactor for the production of steam and Syngasfrom coal, biomass or organic waste utilization is provided witheffective removal of pollutants such as sulfur, mercury, and ash. Thereactor may be used for the gasification of coal to syngas in anintegrated gasification combined cycle (IGCC) process for powergeneration. Syngas is a mixture of gas with varying amounts of carbonmonoxide (CO) and hydrogen gas (H₂).

The reactor may be used in combination with other processes for theproduction of transportation fuels, fertilizers and polymers. Unlike theexisting gasification reactors, the present oxygen-free gasificationreactors do not use oxygen. The elimination of an oxygen plant resultsin the reduction of capital costs, operational costs, reduction of CO₂emissions, and increase in overall efficiency. Being oxygen-free,modular, and scalable, the present oxygen-free reactor provides low costand clean energy production from coal, biomass, organic waste, or anyother form of organic feedstock.

FIG. 1 illustrates a simplified process of oxygen-free gasification,according to one embodiment. The inside of a primary reaction chamber404 of reactor 101 is maintained at temperature below 1000° C., and theinside of a secondary reaction chamber of reactor 101 is maintained at atemperature greater than 1000° C. and at a pressure in excess of 1atmosphere. Organic matter 110 (e.g., coal or organic waste) andsuperheated steam 111 are supplied to reactor 101. Feedstock 110 (e.g.,organic matter) is converted by endothermic chemical reaction withsuperheated steam (H₂O) to syngas 120 (i.e., mixture of carbon monoxideCO and hydrogen H₂) and byproduct 121 (e.g., sulfur or slag). Combustionof fuel 460 with air 450 generates heat for indirect heating to generatesteam 111 and drive endothermic chemical reaction in reactor 101.

According to one embodiment, reactor 101 gasifies coal to syngas 120 inan integrated gasification combined cycle (IGCC) process for powergeneration. Reactor 101 may be used for conversion of biomass to syngasfor producing transportation fuels. The processes of syngas productionby reactor 101 may be applied for producing fertilizers and polymers.

Existing reactors for generating power, or for producing products (e.g.,fuels, fertilizers, and polymers) require costly oxygen plants and dolittle to eliminate or reduce pollutants and other deleteriousbyproducts such as CO₂ and N. Reactor 101 does not require oxygen plantsbecause the core reaction processes do not require oxygen. Reactor 101eliminates pollutants and unwanted byproducts or reactants. Reactor 101,therefore, is significantly less expensive, cleaner, more efficient andreliable than existing reactors using oxygen.

FIG. 2 illustrates a plot of exemplary syngas composition across atemperature range, taken from a publication entitled “Gasification” byChris Higman and Maarten van der Burgt, (ISBN 0-7506-7707-4), which isincorporated herein by reference.

The pressure within primary reactor 404 is maintained at 30 bar. Thesyngas within reactor 101 contains gases such as hydrogen gas (H₂),carbon dioxide (CO₂), methane (CH₄), and steam (H₂O). The content of CO₂and H₂ in syngas exceeds 80% at temperatures over 1000° C. As thetemperature within primary reactor 404 increases, the content of COincreases while that of H₂, CO₂, CH₄, and H₂O decreases.

FIG. 3 illustrates a plot of exemplary syngas composition over apressure range, taken from a publication entitled “Gasification” byChris Higman and Maarten van der Burgt, (ISBN 0-7506-7707-4), which isincorporated herein by reference. The temperature within primary reactor404 is maintained at 1000° C. As the pressure within primary reactor 404increases, the content of CO and H₂ decreases while the content of CO₂,CH₄, and H₂O increase.

FIG. 4 illustrates an exemplary oxygen-free gasification reactor,according to one embodiment. Feedstock 110 (e.g., pulverized coal,petroleum coke, oil sands, biomass, organic waste) is fed through aswirling nozzle in feed injection zone 401 and mixed with superheatedsteam 111 generated by steam generators 403 and 408 in mixing zone 402.Reactor 101 may process slurry, dry solids, or other types of feedstock.To achieve higher efficiency, feedstock may be mixed with CO₂. If drypulverized coal is forcefully injected under high pressure with CO₂, theamount of heat needed to increase the temperature of the carrying waterto steam is eliminated from the overall energy requirement. Thisincreases the overall efficiency.

Feedstock 110 is injected at a high pressure vertically downward in thedirection of gravity and mixed with superheated steam 111 in across-flow pattern as illustrated in FIG. 4. In preheating zone 405(also referred to herein as a heating zone and a preheating zone),syngas or startup fuel 460 is combusted with air 450 to produce therequired heat in primary reactor 404 and generate hot combustion gasestherein. Superheated steam 111 is generated by gas-to-liquid heatexchanger 403 using the hot combustion gases in preheating zone 405.Superheated steam 111 is provided by jets to create sufficientturbulence in mixing zone 402 and is mixed with feedstock 110 prior toentering primary reactor 404.

According to one embodiment, reactor 101 has a high surface area tovolume ratio such that feedstock 110 undergoes gasification as a resultof thermally driven gasification reaction in reactor 101. For example,for a given internal volume of reactor 101, the surface area insidereactor 101 is increased using protruded structures such as fins or rodsthermally connected to the inner walls of reactor 101. As the mixture offeedstock 110 and superheated steam 111 moves downward, solid-gasreaction occurs as it reaches the bottom of primary reactor 404. Theresulting gases make a u-turn and enter secondary reactor 407.Un-gasified solids are periodically recovered from recovery zone 406.The temperature of primary reactor 404 is regulated and maintained belowslag melting temperature to avoid fouling. The fouling temperature isdetermined by various conditions such as the type of feedstock 110, thecomposition of feedstock 110, the type of reactants mixed with feedstock110, and the type of reactions in the reaction chambers.

According to one embodiment, a different series of reactions may occurdepending on the type of feedstock 110 fed to reactor 101 and the typeof reactants mixed with feedstock 110. The temperatures in primaryreactor 404 and secondary reactor 407 may be maintained at differenttemperatures to facilitate and control the series of reactions.Depending the type of reactions occurring in primary reactor 404 andsecondary reactor 407, a solid, liquid, or gas product may be recoveredor extracted therefrom. The recovered liquid or gas exits throughrecovery zone 406.

According to one embodiment, heat pipes with high thermal conductivityare provided between heating zones 405 and 410 and reactor cores 404 and407. The heat pipes transfer heat from heating zones 405 and 410 toreactor cores 404 and 407 to sustain an endothermic reactor process inthe reactor cores 404 and 407. In one embodiment, heat pipes are made ofMolybdenum and filled with liquid Lithium. The heat pipes have adiameter of about 50-100 mm to transport heat over several meters.

According to another embodiment, thermal pipes encompassing heatingzones 405 and 410 and reactor cores 404 and 407 have protrudedstructures such as fins or rods on their surfaces to maximize heatabsorption and radiation. The heat pipes may be welded to the walls ofchambers 404, 405, 407, and 410 and the fins or rods.

According to one embodiment, the primary reactor 404 converts theorganic components of the mixture of feedstock 110 and steam 111 togaseous mixture for the separation and removal of inorganic solids suchas silicate minerals at a lower temperature. The secondary reactor 407drives the syngas reactions further to completion and removes methaneand water to increase the quality of the syngas at a higher temperatureover 1000° C.

According to one embodiment, preheating zone 405 has a high surface areato volume ratio to effectively transfer significant amounts of heat toprimary reactor 404 across dividing wall 470. The hot gases leavingpreheating zone 405 heat second heat exchanger 408 to generate moresuperheated steam 111 to accelerate gasification in mixing zone 402. Thepreferred temperature of steam is about 500° C.

According to one embodiment, recovery zone 406 is compartmentalized totransfer the residual solids from the reactor core 404 and 407 outsidereactor 101. An outer compartment 406 b is evacuated from atmosphereprior to opening to an inner compartment 406 a to prevent anysignificant amount of air from entering reactor cores 404 and 407. Thelow pressure created in the outer compartment 406 b causes rapidtransfer of the residual solids when the inner compartment 406 a to thereactor cores 404 and 407 are closed and the outer compartment 406 b isopened. The process of solid transfer takes place periodically dependingon the type feedstock being processed in reactor 101. The preferredperiod for solids removal is set from energy and mass balance on reactor101, for example, based on the overall size, type of feedstock 110 andthe processing rate of reactor 101.

According to one embodiment, secondary reactor 407 has a high surfacearea to volume ratio to facilitate heat transfer from primary reactor404 across dividing wall 470. The gases in secondary reactor 407experience a higher temperature than that of primary reactor 404 as aresult of being in countercurrent flow and heat transfer from the heatgenerated by the combustion of fuel 462 with air 450 in heating zone410, driving stronger reactions therein. The higher temperature insecondary reactor 407 increases the concentration of CO and H₂ butdecreases that of CH₄ and CO₂, which is the desired outcome. The hotgases leaving secondary reactor zone 407 enter second steam generationzone 408 to produce additional steam in mixing zone 402.

In case of coal gasification, reactor 101 removes un-gasified solids bythe temperature differences between primary reactor 404 and secondaryreactor 407. In other cases, no solids may be removed during thetransition from primary reactor 404 and secondary reactor 407, but otherforms of multi-stage reactions may occur therein due to the indirect butcontrolled heating process in heating zones 405 and 410. For example,primary reactor 404 produces a certain product at a first temperature,and a different reaction occurs in secondary reactor 407 that ismaintained in a second temperature. The product of primary reactor 404may be separated before exiting primary reactor 404. The product ofsecondary reactor 407 may only be produced as a result of the productionand/or removal of the first product in primary reactor 404.

Depending on the type of reactions occurring in primary reactor 404 andsecondary reactor 407, the material of the reactors/heat exchangers doesnot have to have high melting point but required to have a high thermalconductivity such as that of copper and aluminum. For an applicationthat requires the temperature of primary reactor 404 be maintained atless than 100° C. and the temperature of secondary reactor 407 bemaintained between 200-400° C., the reactors/heat exchangers can be madeof aluminum. For another application, copper can be used if thetemperatures inside primary reactor 404 and secondary reactor 407 are tobe maintained at 600° C., and 650-1000° C., respectively.

According to one embodiment, heat exchangers 403 and 408 are used tocool the generated syngas 120 to a temperature suitable for downstreamgas cleaning processes. The cleaned syngas 632 may be fed into a gasturbine for power generation applications.

In heating zone 410, syngas or startup fuel 462 is combusted with air450 to produce heat for gas-solid reactions in primary reactor 404 andsecondary reactor 407. The secondary heat exchanger 408 uses the heatproduced by fuel 462 and air 450 and produce additional superheatedsteam 111. Heating zone 410 has a high surface area to volume ratio toeffectively transfer heat to reaction zones 404 and 407 across thedividing wall 471.

Superheated steam 111 is generated by gas-to-liquid heat exchangers 403and 408 using the combustion gases from heating zones 405 and 410.According to one embodiment, the hot gases leaving heating zone 410enter third steam generation zone 411 to drive a steam turbine for powergeneration.

According to one embodiment, various feeding systems are employed basedon the type of feedstock. In one example, conventional slurry feedersmay be used to dry feed the feedstock (e.g., pulverized coal, petroleumcoke, or oil sands) with CO₂ and mix with steam generated by thecombustion products of the preheating and heating processes inpreheating zone 405 and heater 410. An example of a standard slurryfeeder is GEHO® PD slurry pump manufactured by Weir Group PLC of UnitedKingdom. In another example, biomass or waste may be fed with a pistonor a screw type feeder.

According to one embodiment, reactor core walls 472 are made of materialwith the following properties:

-   -   thermal conductivity greater than 80 W/m ° C.;    -   chemically inert in the carbon monoxide and hydrogen        environment; and    -   high melting point to withstand the heat of combustion in        preheating zone 405 and heater 410, for example, greater than        2500° C.

Reactor core walls 472 must withstand the internal pressure of reactorcores 404 and 407. To maximize thermal conductivity, reactor core walls472 may be fabricated into enclosed structures with larger surface areasuch as the heat radiating surfaces of heat exchangers 403 and 408 andpressure chambers 404, 405, 407, and 410. In one example, MolybdenumAlloy TZM is used for building reactor core walls 472 and heatexchangers 403 and 408. Reactor 101 may be used for other processes andapplications without requiring high temperature for reaction. In thiscase, a different construction material may be used.

The size and capacity of heat exchanger 403 may be determined based onthe overall design and capacity of reactor 101. According to oneembodiment, heat exchanger 403 is a Bowman® exhaust gas heat exchangermanufactured by E. J. Bowman Limited of Birmingham, England. In anotherembodiment, heat exchanger 403 may be a direct firing heat exchanger ifthe waste heat recovered from preheating zone 405 is not sufficient forgenerating superheated steam 111. In yet another embodiment, heatrecovery from the exhaust gas of preheating zone 405 is supplementedwith a direct firing heat exchanger to generated superheated steam 111.

According to one embodiment, reactor core dividing wall 473 is made fromthe same material as the reactor core walls 470 and 471. The dimensionsof reactor core dividing wall 473 are determined based on the overalldesign and optimization of reactor 101.

A smaller dimension of reactor 101 is preferred. The main designobjective for reactor 101 is to achieve the highest ratio of surfacearea to volume for a given reactor capacity. The science and the art tobe applied in the design and optimization of a reactor is well know inthe art and documented in several manuals and books for heat exchangerdesign, for example, “Compact Heat Exchangers” authored by W. M. Kaysand A. L. London. In this case, a countercurrent heat exchanger designmay be applied. Reactor core dividing wall 473 provides a barrier andthermal coupling between primary reactor 404 and secondary reactor 407.Efficient thermal coupling between primary reactor 404 and secondaryreactor 407 is achieved through the extended surface area of reactorcore dividing wall 473. In one embodiment, the extensions of the surfacearea of reactor core dividing wall 473 are achieved by fin extensions483.

According to one embodiment, primary reactor 404 is made of a largenumber of fins to increase the surface area to volume ratio. Dependingon the type of feedstock that reactor 101 processes, the dimensions andsizes of fins may vary. For example, fin extensions are made of sheetsextending along the chamber of primary reactor 404, or rods connectedacross wall 470 separating preheating zone 405 and primary reactor 404.The rods may or may not interface directly with the fins of preheatingzone 405.

According to one embodiment, primary reactor 404 initiates a primarystage in the process where the temperature is lower. The design andconcept of reactor 101 may be applied to other processes where indirectheating drives multi-stage reaction. In the primary stage, feedstock isgasified at a lower temperature to remove the solids. In a subsequentprocess, a certain reaction is activated at a given temperature range.For gasification of coal, operation at a lower temperature below whichrecovery and extraction of softened and agglomerated ash from primaryreactor 404 is eased. Devolatilization of coal takes place in the rageof 350-800° C. In this embodiment, the temperature of primary reactor404 is kept below 1000° C. As a result, all of the ash is separated fromthe coal while the softening and/or melting of the ash is prevented. Forsolid feedstock such as coal, ash content may vary from 2.7% to 40% bymass. Primary reactor 404 and preheating zone 405 are designed andoptimized for specific types of feedstock, and the devolatilization andash separation/extraction processes are controlled accordingly.

According to one embodiment, preheating zone 405 is made of apredetermined number of fins to obtain a particular ratio of fin surfacearea to chamber volume. The ratio is related to the thermal couplingcapacity between preheating zone 405, and steam generators 403 or theneighboring primary reactor 404. The fins of preheating zone 405 may bemade from a material of high thermal conductivity. The fins arethermally welded to reactor core wall 470. Thermal rods or sheets may becoupled to reactor core wall 470 to function as fins. These thermallycoupling internal structures may extend across reactors 405, 404, 407,and 410. The configuration and density of thermally coupling internalstructures may vary depending on the design of reactor 101 andconditions for the intended gasification processes.

Due to the high temperature (e.g., 1800° C.) inside preheating zone 405and heater 410, radiation through surrounding walls is a significantcause of heat transfer. To minimize heat loss, thermal radiation shield474 is placed between refractory brick lining 415 of reactor 101, andpreheating zone 405 and heater 410. Thermal radiation shield 474 is madeof a layer of refractory lining such as Al₂O₃ or other thermallyinsulating material. Thermal radiation shield 474 is separated fromrefractory brick lining 415 of reactor 101 and reactor walls and fins bya layer of air to reduce thermal conduction with refractory brick lining415.

Conventional gasification reactors do not have thermal radiation shield474. With conventional reactors, the inner surfaces of the refractorylining are the lining of the reactor. Thus, the reactants are directlyin contact with the inner surface of a refectory brick lining.

According to one embodiment, refractory brick lining 415 of reactor 101is chemically insulated from both the combustion gases exiting frompreheating zone 405 and heater 410 and the atmosphere inside the reactorcores (i.e., primary reactor 404 and secondary reactor 407).

For producing syngas, the atmosphere inside the reactor core is highlyreducing—the oxide material of refractory brick lining 415 (e.g., Al₂O₃,Fe₂O₃, MgO, CaO) reacts with CO and H₂ to produce CO₂, H₂O and basicmetals such as Fe, Ca, Mg, and Al. The constant chemical attack by theCO and H₂ in the syngas affects service life of refractory brick lining415, and may result in a shutdown for repair. Reactor walls 470 and 471eliminate direct contact of syngas with refractory brick lining 415 andallows for containment of the syngas in the chemically-inert reactorcores.

According to one embodiment, preheating burners 480 and 481 combustfuels 460 and 462 such as natural gas or syngas. The capacity andplacement of preheating burners 480 and 481 are determined by the designconfiguration of reactor 101 to provide heat for primary reactor 404 andsecondary reactor 407 and generate superheated steam 111. Combustion offuels 460 and 462 may be driven by air or oxygen. When air is used, someof the air is supplied as primary air for combustion of fuels 460 and462 and the remaining air is induced through an air inlet as a result ofthe negative pressure created by exhaust 452.

Splitting the combustion air into primary injected through burner 480and secondary induced by a jet of the flame at burner 481 enables theprecise control of the flame shape and length. The induction strengthfor the secondary air is driven by the amount of negative pressureswhich may be created by the downstream fluid moving equipment such as ablower or fan. In this case, the induction fan or blower would belocated downstream of heat exchangers 403, 408, and 411. If oxygen isused, the exhaust gas is injected into reactor 101 to drive the flow ofsolids and ultimately to capture and sequestrate CO₂. Heating burners480 and 481 may be a single burner or multiple burners. Heating burnersmay be positioned vertically (e.g., burner 480) where the flame ispenetrating up through the fins or horizontally (e.g., heating burner481). It is appreciated that different configurations of burners 480and/or 481 are possible without deviating from the scope of the presentsubject matter.

According to one embodiment, solid byproducts such as high ash contentcoal or oil sands are cooled using a bed cooler. Secondary air zone 412may be a solid bed cooler wherein the secondary air flows in to cool theash, sand, or slag, and recover residual heat in the solids.

According to one embodiment, secondary reactor 407 is made of apredetermined number of fins to obtain a particular ratio of fin surfacearea to chamber volume. The ratio is related to the thermal couplingcapacity between secondary reactor 407 and neighboring primary reactor404 and heater 410. According to one embodiment, secondary reactor 407is maintained at a temperature higher than primary reactor 404 (e.g.,1200° C. or higher), to effectuate high temperature gas-phase reactions.At a temperature higher than 1000° C., the ratio of CO+H₂ with respectto CH₄+CO₂ is higher, so that higher quality syngas is produced.

According to one embodiment, the outer surface of refractory bricklining 415 is covered with shell 475. The thickness and material ofshell 475 is determined to sustain high temperature within reactor 101and to provide structural rigidity of reactor 101. In one embodiment,shell 475 is made of steel. The preferred thickness of shell 475 is15-30 mm.

Unlike conventional gasification reactors, the internal cavity ofreactor 101 contains heavily integrated metallic structures. Theinternal structures may be built on a steel base.

According to one embodiment, reactor 101 starts with syngas or startupfuel (e.g., natural gas) to heat preheating zone 405 and heater 410. Asthe temperature of the reactor cores 404 and/or 407 reaches to a desiredtemperature (e.g., higher than 1500° C.), water (e.g., 420, 421, 423) isintroduced into reactor 101 for steam generation, and feedstock (e.g.,slurry or dry coal) is injected into reactor 101. The feed ratesincluding the water flow rates to the reactor core 404 and fuel flowrates to burners 480 and 481 are adjusted until the concentrations ofH₂, CO, H₂O, CO₂ and CH₄ in the product (syngas) approach the desiredvalues. According to one embodiment, the feed rates and fuel flow ratesare measured with sensors and computer controlled. As the steamgeneration rate approaches a predetermined level for a specific reactorand/or the entire plant mass-and-energy balance, the superheated steammay be fed to a turbine for power generation in the case of powergeneration reactor 101. The composition of syngas is monitored. Afterthe composition of syngas is reached to a desired level, the syngas issent to turbine and/or storage tanks An ideal syngas is made only of COand H₂. A plant/reactor designer sets the desired syngas quality basedon the overall optimization of reactor and efficiency of the plant beingdesigned. The design and optimization of such reactors and plants arewell known to the practitioners of the art.

FIG. 5A is a top view of a cylindrical type reactor, according to oneembodiment. The cylindrical type reactor 501 is covered with refractorybrick lining 515 and shell 575. Primary reactor 504 and secondaryreactor 507 are contained in reactor core walls 572, shielded fromrefractory brick lining 515 by radiation shield 574. Dividing wall 570separates primary reactor 504 and secondary reactor 507.

FIG. 5B is a top view of a box-type reactor, according to oneembodiment. The box-type reactor 101 is covered with refractory bricklining 415 and shell 475. Primary reactor 404 and secondary reactor 407are contained in reactor core walls 472, shielded from refractory bricklining 415 by radiation shield 474. Dividing wall 470 separates primaryreactor 404 and secondary reactor 407.

According to one embodiment, syngas is used for producing fertilizers,or other types of products. Nitrogen is a basic component of air, thusis desirable for making fertilizers whose basic chemical compounds isammonium nitrate (NH₄NO₃). If oxygen is used, the exhaust gases made ofCO₂ and H₂O are used as a gasification moderator to control the ratio ofCO with respect to H₂ in the syngas. The more water (steam) is added tothe feedstock, the higher is the hydrogen content of the syngas.However, adding water however reduces the thermal efficiency. Acontrolled amount of water and carbon dioxide may be added to regulatethe ratio of CO and H₂. The recycling of hot exhaust gases in the feederfor injecting feedstock (e.g., pulverized coal) significantly increasesthe efficiency and enables dry feed. Dry feed does not contain waterwhich requires additional heat to increase its temperature to generatesteam. Reduction of the externally provided energy achieves the increaseof the overall efficiency of reactor 101.

According to one embodiment, CO₂ injected with pulverized coal reactswith the coal according to the Boudouard reaction and produces CO andheat energy, as given below:C+CO₂

2CO+171 MJ/Kmol.This reaction is an endothermic reaction that requires heat to driveformation of CO. Reactor 101 allows for the adjustment of heat added forreaction by adjusting the heating rates from burners 480 and 481.

The integrated design of reactor 101 enables higher efficiency thanconventional gasification reactors. Because the source of heat isexternal to primary reactor 404 and secondary reactor 407, CO₂ generatedas a byproduct of gasification is sequestrated without adverselyaffecting the stability of reactor 101, H₂O in the exhaust of preheatingzone 405 and heater 410 are recycled for heat recovery. A greater degreeof moderation for the ratio of CO versus H₂ in the syngas is obtained.

In addition, steam can be injected at a variable rate to increasehydrogen concentration in the syngas. This is not easily achievable inconventional gasification reactors because the increase of steam to theinternal source of heat can cause instability within the reactors 405and/or 407.

FIG. 6 illustrates a block diagram for an exemplary integratedgasification combined cycle, according to one embodiment. For a dry feedapplication, coal 623 is fed without water 622 and is mixed with CO₂ 621in a slurry preparation block 601. The mixture of coal and CO₂ 621 isfed to reactor 603 for generating power. The high pressured steam 628generated in reactor 603 as a result of gasification drives a turbine.The CO₂ in exhaust gas 627 from reactor 603 is captured andsequestrated. The mixture of syngas or startup fuel with air 626 to heatpreheating zone 405 and heater 410. Syngas generated in reactor 603 issent to a COS hydrolysis unit 604 for absorption. COS hydrolysis unitsare well known in the art, thus the details of which will not bediscussed herein. Syngas passed to COS hydrolysis unit 604 is furtherprocessed for cooling and ammonia (NH₃) stripping (e.g., NH₃ strippingunit 605). The syngas is further processed to extract acid gas 631(e.g., sulfuric acid) (e.g., acid stripping unit 606). The ammonia gas629 stripped by NH₃ stripping unit 605 and sulfuric gas stripped by acidstripping unit 606 are fed to a processing plant 630. The cleaned syngas632 may be used to drive a turbine.

According to one embodiment, reactor 603 is integrated with a solar unit610 to preheat water 620 and/or generate steam 111 that is fed toreactor 603.

FIG. 7 illustrates a block diagram for an exemplary biomass to ethanolconversion, according to one embodiment. The mixture of biomass 723 andwater 721 is fed to a slurry preparation block 701 and subsequentlyreactor 702. The high pressured steam 726 generated in reactor 702 as aresult of gasification drives a turbine. The CO₂ in exhaust gas 725 fromreactor 702 is captured and sequestrated. Syngas generated in reactor702 is fed to compressor 703 and subsequently fed to alcohol synthesisreactor 704. The liquefied alcohol is processed for phase separation byphase separation unit 705 and distilled at distillation unit 706 toproduce ethanol 727. The distilled ethanol 727 is used as an alternativefuel to fossil fuels (e.g., gasoline, natural gases). The process ofcoupling a gasifier or a syngas production reactor disclosed herein witha process, for example a Fischer-Tropsch process, for the production ofsynthetic fuels and chemicals is well known and widely practiced.

According to one embodiment, reactor 702 is equipped with varioussensors and meters, for example a mass flow meter, a pressure sensor, atemperature sensor, and a mixture sensor. These sensors and meters areto be placed in locations of the highest and lowest expected values tobe monitored, to measure the mass flow rate, temperature, pressure andspecies concentration of all of the inlet and outlet streams in thereactor. The senor outputs are fed to a main computer for dynamic datamonitoring, processing, and control. In one embodiment, startup andsteady state operating conditions are determined from the calculation ofan energy-and-mass balance process and stored in the main computer fordynamic monitoring and adaptive control. The reactor control system mayinterface with another control system and designed to be integrated withother reactors and/or plants.

While the present system has been shown and described herein in what isconsidered to be the preferred embodiments thereof, illustrating theresults and advantages over the prior art obtained through the presentinvention, the invention is not limited to the specific embodimentsdescribed above. Thus, the forms shown and described herein are to betaken as illustrative, and other embodiments may be selected withoutdeparting from the spirit and scope of the present subject matter.

Embodiments as described herein have significant advantages overpreviously developed implementations. As will be apparent to one ofordinary skill in the art, other similar apparatus arrangements arepossible within the general scope. The embodiments described above areintended to be exemplary rather than limiting, and the bounds should bedetermined from the claims.

What is claimed is:
 1. A method for providing oxygen-free gasificationin a reactor, comprising: combusting syngas with air in an indirectheating zone to generate hot combustion gases, the indirect heating zonehaving a heat exchanger for generating steam by using the hot combustiongases; heating a reaction zone by using the hot combustion gases forheating a reaction zone; mixing feedstock and the steam in a mixingzone, wherein the feedstock comprises organic waste; providing, by themixing zone, a mixture of the feedstock and the steam; and performingoxygen-free gasification in the reaction zone, wherein oxygen-freegasification comprises converting, in a first reactor, the mixture to afirst syngas at a first temperature; and converting, in a secondreactor, the first syngas to a second syngas at a second temperature,the second temperature being higher than the first temperature, whereinthe hot combustion gases remain separated from the steam, the feedstock,the mixture, the first syngas, and the second syngas.
 2. The method ofclaim 1, further comprising mixing the feedstock with CO2.
 3. The methodof claim 1, further comprising mixing the feedstock with the steam inthe mixing zone in a cross-flow pattern.
 4. The method of claim 1,further comprising providing the steam in the form of jets and creatingturbulence in mixing zone.
 5. The method of claim 1, further comprisingcollecting, by a compartmentalized recovery zone, residual solid,liquid, or gas generated in the reaction zone.
 6. The method of claim 1,wherein the second syngas comprises CO2.
 7. The method of claim 6,wherein the CO2 is fed for capture and sequestration.
 8. The method ofclaim 6, wherein the second syngas further comprises hydrogen sulfide.9. The method of claim 8, further comprising extracting the hydrogensulfide from the second syngas.
 10. The method of claim 8, furthercomprising driving a turbine for power generation by using the secondsyngas.
 11. The method of claim 1, further comprising feeding the secondsyngas to a synthesis reactor to generate synthetic fuels.
 12. A methodfor providing oxygen-free gasification in a reactor, comprising:combusting syngas with air in an indirect heating zone to generate hotcombustion gases, the indirect heating zone having a heat exchanger forgenerating steam by using the hot combustion gases; heating a reactionzone by using the hot combustion gases for heating a reaction zone;mixing feedstock and the steam in a mixing zone, wherein the feedstockcomprises organic feedstock; providing, by the mixing zone, a mixture ofthe feedstock and the steam; and performing oxygen-free gasification inthe reaction zone, wherein oxygen-free gasification comprisesconverting, in a first reactor, the mixture to a first syngas at a firsttemperature; and converting, in a second reactor, the first syngas to asecond syngas at a second temperature, the second temperature beinghigher than the first temperature, wherein the hot combustion gasesremain separated from the steam, the feedstock, the mixture, the firstsyngas, and the second syngas.
 13. The method of claim 12, furthercomprising mixing the feedstock with CO2.
 14. The method of claim 12,further comprising mixing the feedstock with the steam in the mixingzone in a cross-flow pattern.
 15. The method of claim 12, furthercomprising providing the steam in the form of jets and creatingturbulence in mixing zone.
 16. The method of claim 12, furthercomprising collecting, by a compartmentalized recovery zone, residualsolid, liquid, or gas generated in the reaction zone.
 17. The method ofclaim 12, wherein the second syngas comprises CO2.
 18. The method ofclaim 17, wherein the CO2 is fed for capture and sequestration.
 19. Themethod of claim 17, wherein the second syngas further comprises hydrogensulfide.
 20. The method of claim 19, further comprising extracting thehydrogen sulfide from the second syngas.
 21. The method of claim 19,further comprising driving a turbine for power generation by using thesecond syngas.
 22. The method of claim 12, further comprising feedingthe second syngas to a synthesis reactor to generate synthetic fuels.